Just had this happen to me as well. I was doing EDDP to EGLL on VATSIM and on final approach for 27L in Heathrow. Disconnected the AP at about 1000ft, and at 500ft, suddenly the engines went off, the whole plane went dark and I crashed right in front of 27L, resulting in uncontrollable bouncing and stalling around. Had to disconnect and return to the menu